The cube I used was a Cosmic GTS2 M from SpeedCubeShop. Using Discount Code “SCR” will get a discount off of your entire order at SpeedCubeShop! Check out their selection of new cubes http://bit.ly/1ZZTCGJ
I would get a lot of questions as to how to put together or take apart a speed cube. Often people seemed to think their cube fell apart when a piece popped out. Tensions might need to be adjusted but the most of the time it's not a faulty or broken cube.